+34. The host_aton() function is supposed to be passed a string that is known
+ to be a valid IP address. However, in the case of IPv6 addresses, it was
+ not checking this. This is a hostage to fortune. Exim now panics and dies
+ if the condition is not met. A case was found where this could be provoked
+ from a dnsdb PTR lookup with an IPv6 address that had more than 8
+ components; fortuitously, this particular loophole had already been fixed
+ by change 4.50/55 or 4.44/33 above.
+
+ If there are any other similar loopholes, the new check in host_aton()
+ itself should stop them being exploited. The report I received stated that
+ data on the command line could provoke the exploit when Exim was running as
+ exim, but did not say which command line option was involved. All I could
+ find was the use of -be with a bad dnsdb PTR lookup, and in that case it is
+ running as the user.